Methods and apparatus for joining sheet metal pieces which do not have perforations are disclosed in our pending U.S. patent application, Ser. No. 438,095 filed on Nov. 1, 1982.
The apparatus disclosed in this application comprises a male die and a female die, and the latter as a stationary anvil with adjacent resilient support members provided with cutting edges. In use, the male die penetrates through the pieces to be joined and between the support members thereby cutting through both sheets. The material between the anvil and male die is then compressed and thereby swaged outward so that it flows behind or beyond the edges of the incisions previously formed in the sheet adjacent the female die. In order to permit such lateral swaging, the support members are adapted to flex outwards from the anvil.